1. Department of Biochemistry and Molecular Biology, University of Parma, Via G.P. Usberti 23/A, 43100 Parma, Italy, Department of General and Inorganic Chemistry, University of Parma, Via G.P. Usberti 17/A, 43100, Parma, Italy, National Institute for Biostructures and Biosystems, Viale Medaglie d’Oro 305, 00136 Roma, Italy, and Department of Medicinal Chemistry and Institute for Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia, 23298-0540